Apparatus and method for adjusting a focal point using an imaging device including phase difference detection pixels are disclosed. An apparatus is provided that includes an imaging device comprising an optical aperture disposed between a micro lens and a photoelectric conversion unit of each of a plurality of pixels, the optical aperture being eccentric with respect to an optical axis of the respective micro lens, the imaging device configured to output a phase difference signal; and a control unit that detects a focal position from the phase difference signal detected from entire pixels of the imaging device to drive a focus lens and that adjusts a focal point.